The SQL example is given below to count number of character occurrences in a string in Oracle. You can more customize the SQL as per your requirement.
[code type="SQL"]SELECT replace(a_string, ' ', 'spaces') Character, COUNT (a_string) Occurrences
FROM ( Â Â SELECT SUBSTR (a_string, LEVEL, 1) a_string
FROM (SELECT lower('a quick brown fox jumps right over the lazy dog.')
a_string
FROM DUAL)
CONNECT BY LEVEL <= LENGTH (a_string))
GROUP BY a_string  [/code]
The above SQL will count number of occurrences in a string and output would be as below:
CHARACTER OCCURRENCES
------------------ -----------
q               1
i               2
k               1
h               2
e               2
z               1
o               4
j               1
s               1
d               1
r               3
g               2
a               2
b               1
p               1
t               2
c               1
u               2
w               1
x               1
y               1
CHARACTER Â Â Â Â Â OCCURRENCES
------------------ -----------
. Â Â Â Â Â Â Â Â Â Â Â Â Â Â 1
spaces            9
n               1
f               1
m               1
v               1
l               1
28 rows selected.